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Advanced micro-wave sensor technology for robust, remote maintainable control system for concrete products manufacturing


Based on innovative multidimensional approaches for data processing, advanced control strategies and new enhanced multiple-frequency microwave sensor systems an efficient and powerful control system for the concrete production has been developed. Functional prototypes of the PC- based control system and the new advanced multiple-frequency sensor systems for on-line measurement of raw material moisture and characteristics has successful applied at several production lines within the different production facilities of the concrete producing MICROSEC project partners. The multiple sensor based control system has been developed in order to remain the competitiveness of SMEs in the concrete industry applying innovative and cost efficient solutions offered by modern information and sensor technologies in this traditional industrial sector where these advanced technologies are not market available up to now. The overall system represents a integrated solution where different innovative control procedures and the advanced multiple-frequency sensor systems co-operate to achieve and guarantee important features like high robustness, high productivity, high product quality, high availability, easy maintainability and high autonomy for the industrial production system. It was one of the key objectives of the project to realise these essential system characteristics for a traditional industrial application area where the available resources and possible investments on SME site are limited. The modern object-oriented design with the application class library and the open architecture of the PC-based multiple sensor control system, field bus for the sensor strongly contribute that integration and interfacing of the advanced multiple sensor control system in the individual and often very heterogeneous production environment is simplified. In scope of intensive industrial tests series at the different SME partner sites within various production facilities with different individual constraints the observed results have clearly demonstrated that the PC-based MICROSEC-Control System is able to fulfil the stated ambitious objectives. The Advanced Multiple Sensor based Control System for high quality Concrete Production developed in scope of the MICROSEC project consists two innovative system parts. The MICROSEC Control Software System with advanced procedures implemented in C++ running under the MS-NT 4.0. and the intelligent MICROSEC Multiple Frequency Micro-Wave Sensor System with a micro controller for sensor data pre processing and a CAN-bus interface for the communication between the control system and the sensor systems. The MICROSEC Control Software System includes several innovative procedures which have been developed to make optimal use of the enhanced information and improved accuracy delivered from the MICROSEC Multiple Frequency Microwave Sensor System. Improved recipe accuracy, high product quality, high robustness with respect to unpredictable disturbances, easy maintainability and adaptability are some of the essential features achieved by a powerful set of innovative procedures, variable control strategies, the object oriented implementation concept and the open system architecture: -High efficient and reliable information processing concept of the raw sensor data in reference to process states, recipe dependencies applying enhanced multidimensional filtering algorithms. -Redundancy and consistency mechanisms have been implemented to introduce failsafe operation ability of the concrete production even in the event of some single sensor malfunction or performance degradation happens. -Internal supervisory mechanisms based on the process model and sensor data are monitoring the accuracy, calibration and correctness of the measurement values. -Multidimensional interpolation approach automatically determines the calibration curves for new recipes. By means of this the maintenance effort and potential failure sources can be significantly reduced. -The usage of a width spread standard operation system for the software platform (MS Windows NT 4.0) provides easy and low cost access to a large amount of already existing software tools and interfaces. -The application of standard PC-technology for the hardware platform reduces the investment costs and allows the usage of components produced for the mass market. -The object oriented design and implementation of MICROSEC software in C++ are very useful/helpful. Future system extensions can be easily implemented, updates and maintenance tasks can also be executed more easily. -Portability is a further advantage of using standard OS-Systems, standardised HW-components and a standardised implementation language. -The ability for remote maintenance and the system operation through a GUI are additional reasonable features contributing for the easy system usability. The MICROSEC Multiple Frequency Sensor System developed in the scope of MICROSEC has several essential features which are of high importance for the realisation of an innovative computer and sensor based control system for concrete production. In detail, the following essential system features will strongly be supported by the multiple frequency sensor systems: -Improved Moisture Accuracy and Performance: The usage of multiple frequencies and material temperature allows the application of advanced multiple sensorial data processing algorithms to get more precise moisture measurements (accuracy <+/- 0.2%) or to even get information about the actual amount of the finest sized sand particles in the aggregates. -Improved Robustness, Reliability and Availability: These features are provided by a set of measurements and design decisions. For communication between the sensors and the MICROSEC control system, standard interfaces and a common industrial protocol are used ( CAN-Bus). A micro controller module at the sensor site includes software/algorithms for data pre-processing tasks, BIT-functions (Built-In-Test) and individual sensor data/parameter configuration administration. Less production of waste and increased productivity will be the key benefits. -Easy Installation, Operation and Maintenance: Circuit and board design for the sensor electronic have been done taking into account the very strong environmental conditions of the application area on the concrete production site. The moderate dimensions of the sensor housing lead to a high flexibility regarding the possibilities to install the sensors in the best suitable position for getting best measurement results. The micro controller module at the sensor site include pre-calibration curves which make sure that each individual sensor has the same nominal sensitivity behaviour and therefore can be easily substituted. The primary potentials w.r.t. benefits for the end-user companies based on the introduction of the advanced MICROSEC technologies are of the following types: -Increase in the quality/workability of raw (wet) concrete. -Increased productivity and throughput. -Savings on operating costs (energy, maintenance, spare parts) for the mixer due to saved dry mixing cycles and, therefore, reduced mixing time per batch. Additional savings and benefits will be achieved from: -Reduced production of waste and defective goods. -Extended flexibility for the production planning task based on the increased mixer capacity. -Permanent documentation and supervision of process & quality relevant parameters.